In manufacturing an electronic device such as a semiconductor device, a target object is accommodated within a decompression processing vessel and a process is performed on the target object. The process performed on the target object is, for example, a plasma process, and more specifically, an etching process or a film forming process. In a processing apparatus for this process, a mounting table is provided within the processing vessel and the target object is mounted on the mounting table. For this reason, the mounting table includes an electrostatic chuck.
A single-electrode type and a double-electrode type have been known as the electrostatic chuck. A single-electrode type electrostatic chuck includes a single electrode and dielectric films, and the electrode is provided within the dielectric films. Further, in the single-electrode type electrostatic chuck, a DC voltage is applied to the electrode. In the single-electrode type electrostatic chuck, when the DC voltage is applied to the electrode, a surface of the electrostatic chuck is electrified. Furthermore, since a target object is electrically grounded, a surface of the target object facing the electrostatic chuck is electrified with polarities opposite to those of the surface of the electrostatic chuck. Thus, a potential difference between the surface of the electrostatic chuck and the target object is made, so that the target object is adsorbed on the electrostatic chuck.
A double-electrode type electrostatic chuck includes two electrodes and a dielectric film, and the two electrodes are provided within the dielectric film. In the double-electrode type electrostatic chuck, DC voltages different from each other are respectively applied to the two electrodes. In the double-electrode type electrostatic chuck, when the DC voltages different from each other are respectively applied to the two electrodes, there is made a potential difference within the electrostatic chuck and a positively charged region and a negatively charged region are formed on the surface of the electrostatic chuck. Further, a surface of the target object facing the electrostatic chuck is electrified with polarities opposite to those of the surface of the electrostatic chuck. Thus, a potential difference between the surface of the electrostatic chuck and the target object is made, so that the target object is adsorbed on the electrostatic chuck. These single-electrode type and double-electrode type electrostatic chucks are described in Japanese Patent Laid-open Publication No. 2013-016554.
Patent Document 1: Japanese Patent Laid-open Publication No. 2013-016554
In the single-electrode type chuck and the double-electrode type electrostatic chuck described above, the surfaces of the electrostatic chucks can be easily electrified. By way of example, a product generated by performing a process on the target object adheres to the surface of the electrostatic chuck, so that a modified layer is formed and the modified layer can be easily electrified. If the surface of the electrostatic chuck is modified, an abnormality in electrification may occur and an adsorptive force with respect to the target object may be decreased. Further, even after the application of the voltage to the electrode is stopped, electric charges remaining on the surface of the electrostatic chuck may generate the Coulomb force between the electrostatic chuck and the target object. Since it is difficult to find out an amount of remaining electric charges accurately, it may also be difficult to remove the electric charges from the surface of the electrostatic chuck.
Therefore, in the present technical field, it has been required to suppress the adsorptive force of an electrostatic chuck from being decreased and also required to suppress the electric charges from remaining on the surface of the electrostatic chuck.